The present application claims priority from Canadian Patent Application No. 2,260,695 the contents of which are incorporated herein by reference.
The present invention relates generally to monitoring and control systems, and more specifically relates to an integrated monitoring, diagnostics, shut-down and control system.
Electronic systems of a machinery can perform various functions such as monitoring, diagnostics, shutdown, and control.
Monitoring refers to the ability to acquire readings from electronic sensors via analog to digital conversion or open/closed contacts of sensors and to be able to display the numerical readings or status and/or to be able to store the result by electronic means.
Diagnostics refers to the ability to determine the mechanical condition and performance of a machine from the sensors which are monitored. The diagnostic results may be determined by alarm values of sensor data, or calculated values derived from the sensor data by various mathematical techniques or by means of logic, fuzzy logic, probabilities, and/or rules implemented by software. The mechanical condition refers to the fitness of mechanical parts that form parts of the machine to perform the function required by the machine. Examples of mechanical parts may be a bearing, a valve, or a piston ring in an engine. The performance refers to the ability of the machine to perform its function such as turning a shaft at the desired speed, or to generate a flow of gas at the desired pressure and flow rate.
Shutdown refers to the ability to shutdown a machine that is operating in a condition which is considered as unsafe or likely to cause the machine to damage itself or associated machinery. An example is the shutdown of an engine with a abnormally low oil level or low oil pressure. The shutdown function causes the machine to stop operating in response to a specified signal or a combination of electronic signals from analog and/or digital sensors that sense certain machine conditions. An example is a rotational speed sensor that generates a signal when the rotational speed of a shaft exceeds a pre-determined setting which in turn causes the shutdown system to shut off the fuel or source of energy to the device causing the shaft to rotate.
Control refers to the ability of an electronic system to read an electronic analog or digital sensor signal and generate an output analog or digital signal which controls an actuator to control an attribute of the machine. An example is the control of coolant temperature with the open/close position of a valve in the coolant flow line. When the coolant temperature rises causing a high reading on the temperature sensor, the control system changes an electronic output current or voltage to open the control valve which allows more cool water to flow.
System refers to the combination of electronic hardware which can read sensor outputs, can generate control signals for actuators, contacts or switches for the purposes of control and/or enunciation, and software which causes the electronic hardware to respond in the desired manner.
In the case of machinery with reciprocating pistons, such as reciprocating engines, reciprocating compressors used for compressing gases, and reciprocating pumps used for pumping liquids, current electronic system are designed to perform a combination of the functions.
The performance of the functions of shutdown and control is currently integrated within control systems, such as systems using Programmable Logic Controllers (PLC""s). Many of these control systems have the ability to perform these functions with hardware or software processes such as the proportional, integral, derivative (PID) functions. Such systems can acquire analog and digital signals and can generate analog and digital outputs. These systems generally follow a ladder logic or flow diagram method of operation. Basically the loop is repeated while the system is operating. The key feature of these systems is the ability to ensure a response within a guaranteed time (such as 0.5 s, 0.1 s). Some of the systems use a real time operating system to perform the tasks in addition to being able to perform electronic communication with other devices (RS232, RS485 etc.). However, such systems do not have the ability to acquire and manipulate analog inputs at a data rate higher than 10 to 100 times per second. As well, such systems generally do not have the computational capability to perform diagnostics beyond simple threshold alarms.
There are a number of systems available that perform monitoring using computer technology with data sampling rates well above 1000 per second. Examples of such systems are the Beta-trap On-line made by Liberty Technology, the Model 6100 made by Windrock systems, and the SCXI signal conditioning system made by National Instruments. Normally these monitoring units have the capability for communications. Some of the most advanced of these systems have software diagnostic capability. The monitoring involves the acquisition of a contiguous stream of data followed by the processing of the data to either generate a numerical result or store the data for later processing. All of these monitoring systems cannot, by the nature of their single tasking design, perform the monitoring and shutdown capabilities at the same time as the monitoring.
Because of the designs currently used for shutdown/control and monitoring/diagnostics each of them are not capable of adding the complementary capability.
There is a need in the art for a system that integrates the functions of shutdown and/or control of a machinery with the functions of monitoring and/or diagnostics of a machinery.
It is an object of the invention to provide a integrated monitoring, diagnostics, shut-down and control system for machinery.
In an embodiment of the invention, there is provided an integrated monitoring, control and shut-down (IMCS) system for monitoring and controlling the operation of a machinery. The IMCS system includes: input ports for receiving input sensor signals indicative of conditions of the machinery that require monitoring and output ports for outputting control signals to actuators of the machinery that require control. The IMCS system also includes signal conversion means coupled to the input and output ports, for converting the input sensor signals into data samples and for converting control data into control signals. Furthermore, the IMCS system comprises memory means, said memory means storing at least a software application comprising a communication protocol. The IMCS system also includes a data processor for controlling operation of the signal conversion means, for processing the data samples into calculated values, for sending selected calculated values to be stored into the memory means, for calculating control data, said data processor operating according to said software application. The IMCS further includes a communication bus coupling the data processor, the signal conversion means, the memory means, according to said communication protocol, and a power supply for providing power for the operation of the system.
The invention can be used for monitoring, controlling, diagnosing and determining the performance of machines used to develop mechanical energy such as reciprocating engines, machines driven by a rotating shaft such as electrical generators, rotating and reciprocating compressors, rotating and reciprocating pumps, propellers (air and water), water and gas turbines, and the like.
In one of its aspect, the invention also provides a data acquisition process for use in the monitoring and control of a rotating equipment comprising a shaft, the method comprising the steps of sampling a condition sensor output indicating a condition of the rotating equipment that requires monitoring, for obtaining a condition signal; sampling a marker sensor indicating the rotational position of said shaft, for obtaining a rotation marker signal; and combining the condition signal and the rotation marker signal.